This module defines functions to help use the Google Test infrastructure. Two mechanisms for adding tests are provided. gtest_add_tests() has been around for some time, originally via find_package(GTest). gtest_discover_tests() was introduced in CMake 3.10.
The (older) gtest_add_tests() scans source files to identify tests. This is usually effective, with some caveats, including in cross-compiling environments, and makes setting additional properties on tests more convenient. However, its handling of parameterized tests is less comprehensive, and it requires re-running CMake to detect changes to the list of tests.
The (newer) gtest_discover_tests() discovers tests by asking the compiled test executable to enumerate its tests. This is more robust and provides better handling of parameterized tests, and does not require CMake to be re-run when tests change. However, it may not work in a cross-compiling environment, and setting test properties is less convenient.
More details can be found in the documentation of the respective functions.
Both commands are intended to replace use of add_test() to register tests, and will create a separate CTest test for each Google Test test case. Note that this is in some cases less efficient, as common set-up and tear-down logic cannot be shared by multiple test cases executing in the same instance. However, it provides more fine-grained pass/fail information to CTest, which is usually considered as more beneficial. By default, the CTest test name is the same as the Google Test name (i.e. suite.testcase); see also TEST_PREFIX and TEST_SUFFIX.
Automatically add tests with CTest by scanning source code for Google Test macros:
gtest_add_tests(TARGET target
[SOURCES src1...]
[EXTRA_ARGS arg1...]
[WORKING_DIRECTORY dir]
[TEST_PREFIX prefix]
[TEST_SUFFIX suffix]
[SKIP_DEPENDENCY]
[TEST_LIST outVar]
)
gtest_add_tests attempts to identify tests by scanning source files. Although this is generally effective, it uses only a basic regular expression match, which can be defeated by atypical test declarations, and is unable to fully “split” parameterized tests. Additionally, it requires that CMake be re-run to discover any newly added, removed or renamed tests (by default, this means that CMake is re-run when any test source file is changed, but see SKIP_DEPENDENCY). However, it has the advantage of declaring tests at CMake time, which somewhat simplifies setting additional properties on tests, and always works in a cross-compiling environment.
The options are:
include(GoogleTest)
add_executable(FooTest FooUnitTest.cxx)
gtest_add_tests(TARGET FooTest
TEST_SUFFIX .noArgs
TEST_LIST noArgsTests
)
gtest_add_tests(TARGET FooTest
EXTRA_ARGS --someArg someValue
TEST_SUFFIX .withArgs
TEST_LIST withArgsTests
)
set_tests_properties(${noArgsTests} PROPERTIES TIMEOUT 10)
set_tests_properties(${withArgsTests} PROPERTIES TIMEOUT 20)
For backward compatibility, the following form is also supported:
gtest_add_tests(exe args files...)
include(GoogleTest)
set(FooTestArgs --foo 1 --bar 2)
add_executable(FooTest FooUnitTest.cxx)
gtest_add_tests(FooTest "${FooTestArgs}" AUTO)
Automatically add tests with CTest by querying the compiled test executable for available tests:
gtest_discover_tests(target
[EXTRA_ARGS arg1...]
[WORKING_DIRECTORY dir]
[TEST_PREFIX prefix]
[TEST_SUFFIX suffix]
[NO_PRETTY_TYPES] [NO_PRETTY_VALUES]
[PROPERTIES name1 value1...]
[TEST_LIST var]
[DISCOVERY_TIMEOUT seconds]
[XML_OUTPUT_DIR dir]
[DISCOVERY_MODE <POST_BUILD|PRE_TEST>]
)
gtest_discover_tests() sets up a post-build command on the test executable that generates the list of tests by parsing the output from running the test with the --gtest_list_tests argument. Compared to the source parsing approach of gtest_add_tests(), this ensures that the full list of tests, including instantiations of parameterized tests, is obtained. Since test discovery occurs at build time, it is not necessary to re-run CMake when the list of tests changes. However, it requires that CROSSCOMPILING_EMULATOR is properly set in order to function in a cross-compiling environment.
Additionally, setting properties on tests is somewhat less convenient, since the tests are not available at CMake time. Additional test properties may be assigned to the set of tests as a whole using the PROPERTIES option. If more fine-grained test control is needed, custom content may be provided through an external CTest script using the TEST_INCLUDE_FILES directory property. The set of discovered tests is made accessible to such a script via the <target>_TESTS variable.
The options are:
Specifies how long (in seconds) CMake will wait for the test to enumerate available tests. If the test takes longer than this, discovery (and your build) will fail. Most test executables will enumerate their tests very quickly, but under some exceptional circumstances, a test may require a longer timeout. The default is 5. See also the TIMEOUT option of execute_process().
Note
In CMake versions 3.10.1 and 3.10.2, this option was called TIMEOUT. This clashed with the TIMEOUT test property, which is one of the common properties that would be set with the PROPERTIES keyword, usually leading to legal but unintended behavior. The keyword was changed to DISCOVERY_TIMEOUT in CMake 3.10.3 to address this problem. The ambiguous behavior of the TIMEOUT keyword in 3.10.1 and 3.10.2 has not been preserved.
Provides greater control over when gtest_discover_tests() performs test discovery. By default, POST_BUILD sets up a post-build command to perform test discovery at build time. In certain scenarios, like cross-compiling, this POST_BUILD behavior is not desirable. By contrast, PRE_TEST delays test discovery until just prior to test execution. This way test discovery occurs in the target environment where the test has a better chance at finding appropriate runtime dependencies.
DISCOVERY_MODE defaults to the value of the CMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE variable if it is not passed when calling gtest_discover_tests(). This provides a mechanism for globally selecting a preferred test discovery behavior without having to modify each call site.